Columnaris Disease

Columnaris disease has been known to aquarists by many names. Since it so often attacks Black Mollies, it has been referred to as "Black Molly Disease." Others call it "Body Fungus," "Mouth Fungus," "Slime Disease" and "Body Rot." It is preferred that the disease be known by the organism causing it.

Scientifically the disease has been known by several names. When Davis first described it in 1922 he named it Bacillus columnaris (pronounced ba-sill-uscolumn-na-ris), a more exacting description was impossible at that time as he was unable to isolate the causative organism in a pure culture to study it more closely. It took 23 years before one of Davis' students Laura Garnjobst, was able to isolate the organism and recognize it as a myxobacterium. The name was therefore changed to Cytophaga columnaris (sy-toe-fay-ga) by Garnjobst. Further study has resulted in the disease being known as Chondrococcus columnaris (kahn-dro-cock-us), a slime bacterium.

Range of the Disease
The disease may attack nearly all the freshwater tropical fishes. There is evidence that it is more rampant upon those species of fishes whose natural environment is in temperate water (45-65°F), but are being maintained in a tropical environment (72-85°F.) Garnjobst found the optimum temperature for the organism's growth was between 77 and 88°F, roughly the temperature of tropical aquaria. Mollies are fishes that ordinarily inhabit temperate waters, but once they are netted and shipped north as aquarium fishes, they are maintained in warmer water. It is this bacterium which is most often responsible for the infection in Mollies and other live-bearing fishes which are raise in Florida waters.

Symptoms of the Disease
Columnaris disease manifests itself quite emphatically. Beginning with a fading, bluish-white body spot, the disease spreads over the body of the fish until there are several large patches of a mucous-like slime covering the body of the victim. Fins become closed and frayed, the fish may begin to shimmy (usually most live-bearers begin shimmying before the infection has reached this stage), and finally they die.

On catfish (scaleless) and less commonly on other fishes, there is a reddish edge to the infectious ring. This ring is due to hyperemia.

Identify the Disease
Microscopic examination is about the only sure way of observing the bacterium. Scrape a bit of material from the infected area, and prepare it on a slide for high power microscopic examination. The bacterium is a long, rod-like organism about half a micron in thickness and from 5 to 10 microns in length. The organism can move with snake-like motion, spasmodically. One of the most characteristic movements is to turn one end slowly in a circle while the other remains stationary and forms a pivot on which the entire rod revolves.

How Do Fishes Get the Disease
The bacterium usually gains entrance to the host through an injury. They are found most concentrated in the connective tissues, but are also found throughout the epithelial and other tissues. Once they attack the dermis of the fish, the scales above the site of infection usually fall off. One of the most ordinary points of infection of tropical fishes is the mouth. Most fishes shipped from Florida before the widespread use of plastic bags had injuries to their mouths from the rough linings of the fish cans. In 99 cases out of a hundred these fishes would become infected with columnaris disease and their mouths and lips would become white with the infection. The hobbyists know this infection as "Mouth Fungus;" actually this is not a fungus infection at all. In time the disease actually eats away the tissues of the lips and mouth and the fish dies.

The disease is fairly infectious, though healthy fishes are easily kept free of the disease. Most livebearers get it especially after having been moved into fresh water, or having their water changed for other reasons. Fishes freshly arrived from another locale are also very susceptible to this infection. Usually the disease will strike at a whole tankful of the same kind of fish, pointing out that conditions in the aquarium are not proper. Fortunately, there is a very simple, positive cure.

Treatment of the Disease
Tetracycline (Tetracyn or Terramycin being equally good), a product manufactured by the Chas. Pfizer Co., is practically a specific cure for this dread disease. If the 250 mg. capsule form of Tetracycline is used, add the powder from 4 capsules, making one gram, to some warm water, dissolve the powder and add it to the aquarium in which the fishes are being treated. This dosage seems equally effective for aquaria containing from 2 to 12 gallons of water. For larger tanks add 100 mg. per gallon.

There is a form of Terramycin now available which is already dissolved and has a strength of 25 mg. of Terramycin per cc. This is a superior product for dealer, importers, collectors, etc., as there is no waste and it is simple to administer.

The treatment should be administered daily, for three days, with a 50% change in the water every day. Be sure to use water that has been aged and which is of the same pH and temperature as that in which the fishes are being treated. This treatment is 100% effective if applied immediately upon recognition of the disease.

Columnaris disease is so common with imported fishes and livebearers that most dealers and jobbers of aquarium fishes add 500 mg. of Tetracyn per 10 gallon aquarium as a prophylaxis.